VOCs treatment system for UV coating spraying waste gas

Abstract

The utility model discloses a VOCs (Volatile Organic Compounds) treatment system for UV (Ultraviolet) coating spraying waste gas, and relates to the technical field of waste gas treatment. Wherein the VOCs treatment system comprises a filtering and concentrating system and a heat utilization module which are connected in sequence. The filtration and concentration system comprises a wet pretreatment unit, a dry pretreatment unit and a zeolite rotating wheel adsorption and concentration unit which are connected in sequence; the heat utilization module comprises a catalytic combustion unit, and the zeolite runner adsorption and concentration unit is connected with the catalytic combustion unit. The waste gas treatment system disclosed by the utility model can be used for effectively treating acrylic ester, reducing energy consumption and enabling purified gas to reach the standard.

Description

Technical Field

[0001] The utility model relates to the technical field of waste gas treatment, and more specifically to a VOCs treatment system for UV paint spraying waste gas. Background Art

[0002] UV coating, also known as ultraviolet curing coating, is a new type of green and environmentally friendly coating material.

[0003] The UV coatings used in my country are mainly acrylic polyurethane. The paint mist produced by UV coatings has high viscosity and is difficult to handle. By consulting relevant papers and visiting domestic UV coating spraying companies, we found that the main problems are as follows:

[0004] ① UV paint mist contains a large amount of viscous resin, and the photosensitizer, cross-linking monomer, and solvent contained in it are difficult to solidify. The paint mist is very sticky and can easily cause blockage in the paint mist exhaust gas collection system and treatment system;

[0005] ② Paint mist exhaust contains high levels of organic matter, making it difficult to remove;

[0006] ③ The paint mist contains a large amount of ester and ether organic substances, which are easy to catch fire when exposed to sparks or increased temperature.

[0007] ④ When UV coatings are used for spraying small-volume objects such as plastic bottle caps and cosmetic packaging bottles, the effective utilization rate of UV paint is low, averaging 50%, resulting in a large amount of invalid paint in the paint mist.

[0008] At present, the treatment technologies for UV paint mist VOCs used by domestic enterprises include low-temperature plasma, UV photocatalytic oxidation, secondary activated carbon adsorption, catalytic combustion (RCO), regenerative thermal combustion (RTO) and other treatment processes, but many problems were found in the application process:

[0009] ① The problem with low-temperature plasma technology and UV catalytic oxidation technology is that the highly viscous UV paint mist will clog the exhaust gas collection system and treatment system, and it is easy to catch fire when encountering sparks or rising temperatures, making it difficult for exhaust gas VOCs emissions to meet standards stably.

[0010] ② Catalytic combustion treatment technology requires activated carbon or filter cotton as a pretreatment method. UV paint mist blocks the activated carbon pores or filter cotton, which will greatly reduce the service life of the activated carbon and filter cotton, generate a large amount of hazardous waste (waste activated carbon and filter cotton), and increase the cost of hazardous waste disposal; in addition, serious blockage of honeycomb ceramic catalysts will also affect the VOCs removal efficiency.

[0011] ③ Regenerative combustion technology can efficiently decompose UV paint mist VOCs waste gas, but due to the high concentration and large volatility of UV paint mist VOCs waste gas, the presence of combustibles, combustion-supporting materials and ignition sources, exceeding the explosion limit, the possibility of combustion and explosion is relatively high.

[0012] ④ The activated carbon adsorption method mainly uses activated carbon with a strong adsorption effect to adsorb paint mist VOCs to achieve the effect of removing harmful substances. The activated carbon adsorption method has the advantages of simple operation and simple equipment. However, the disadvantage of this method is that the cost is high, and the use of activated carbon adsorption alone requires constant replacement, causing secondary pollution. The replaced waste activated carbon is a hazardous waste with high disposal costs.

[0013] ⑤Membrane separation technology mainly relies on the characteristics of polymer membranes to penetrate into waste gas under a certain pressure to separate organic matter and VOCs. Membrane separation technology is widely used in industries such as petrochemicals and food processing. The advantage of membrane separation technology is that it can effectively separate organic pollutants in high-concentration and low-flow waste gas, but its disadvantage is that it is more expensive.

[0014] Therefore, in view of the current treatment status of acrylate-containing VOCs waste gas, it is an urgent problem that technicians in this field need to solve to develop a waste gas treatment system that can effectively treat acrylates and make the purified gas meet the standards. Summary of the invention

[0015] In view of this, the utility model provides a VOCs treatment system for UV paint spraying waste gas. Based on the analysis of the influencing factors of acrylate polymerization, the system accelerates acrylate polymerization in the front-end pretreatment stage, so that the waste gas containing no acrylate or a small amount of acrylate enters the "zeolite rotor + catalytic combustion" system at the back end, which can solve the production and environmental protection problems caused by substandard waste gas treatment, easy damage to environmental protection equipment, and high investment for the acrylate-using industry. The back end adopts the optimized "zeolite rotor + catalytic combustion" waste gas treatment technology. Through multiple experimental studies and project practices, the conventional "zeolite rotor + catalytic combustion" technology is upgraded and improved. After optimization, the system can achieve the purpose of high-temperature flue gas waste heat recovery and energy consumption reduction through multiple recycling of the internal heat of the system. It is an optimization and improvement of the conventional VOCs treatment technology with high energy consumption, and it conforms to the concept of energy conservation and carbon reduction.

[0016] In order to achieve the above-mentioned purpose, the utility model provides a VOCs treatment system for UV paint spraying waste gas, including a filtering and concentration system and a heat utilization module connected in sequence.

[0017] Furthermore, the filtration and concentration system includes a wet pretreatment unit, a dry pretreatment unit and a zeolite rotor adsorption and concentration unit which are connected in sequence; the heat utilization module includes a catalytic combustion unit; and the zeolite rotor adsorption and concentration unit is connected to the catalytic combustion unit.

[0018] Furthermore, the zeolite rotor adsorption concentration unit comprises: a zeolite rotor and an adsorption fan; wherein the front end of the zeolite rotor is connected to the dry pretreatment unit, and the rear end is connected to the catalytic combustion unit and the adsorption fan respectively.

[0019] Furthermore, the VOCs treatment system for UV paint spraying exhaust gas of the utility model also includes an exhaust pipe, and the tail end of the adsorption fan is connected to the exhaust pipe.

[0020] Furthermore, the wet pretreatment unit includes: a plurality of spray towers connected in series; and the dry pretreatment unit includes: a multi-stage filter.

[0021] Furthermore, the catalytic combustion unit includes a desorption heat exchanger and a desorption fan.

[0022] Preferably, the desorption heat exchanger is connected to the desorption heater and the zeolite rotor in sequence, and the rear end of the zeolite rotor is connected to the front end of the desorption heat exchanger to form a heat utilization branch one.

[0023] The rear end of the desorption fan is connected to the front end of the exhaust gas heat exchanger, the exhaust gas heat exchanger is connected to the electric heater, the catalytic reactor and the desorption heat exchanger in sequence, and the rear end of the desorption heat exchanger is connected to the front end of the exhaust gas heat exchanger, and the front end of the desorption fan is connected to the zeolite wheel, forming a second heat utilization branch.

[0024] The technical concept of adopting the above technical scheme is: due to the release of heat by the catalytic decomposition reaction, the temperature of the high-temperature purified gas coming out of the catalytic reactor can reach 250-550°C, wherein the high-temperature purified gas discharged from the catalytic reactor transfers heat to the desorbed purge gas through the desorption heat exchanger, and then the purge gas is further heated by the desorption heater to reach the desorption temperature of the zeolite wheel; after the high-temperature purified gas passes through the desorption heat exchanger, the heat is transferred to the VOCs desorbed exhaust gas through the exhaust gas heat exchanger, so that the temperature of the VOCs desorbed exhaust gas is close to the temperature required for the catalytic reaction, thereby reducing the use of electric heaters.

[0025] The beneficial effect of adopting the above technical solution is: with this energy-saving design, the high-temperature purified gas from the catalytic reactor can undergo multiple heat exchanges, so that a large amount of heat energy can be returned to the heating section of the system for recycling, reducing the additional supply and loss of heat.

[0026] Preferably, the electric heater is a multi-stage electric heater, which uses intelligent setting to control the start and stop of the heating tube. The system can control the start and stop time and the number of openings of the electric heater according to different temperature ranges, and reasonably control the energy consumption of electric heating. The entire system reduces the energy consumption of system operation by controlling the energy consumption of the start and stop operation of the electric heater and recycling the heat.

[0027] The beneficial effects of the above technical solution are as follows: the zeolite rotor uses zeolite adsorbent, which can be desorbed at a higher temperature, with higher safety performance and longer service life. The high-concentration exhaust gas from the zeolite concentration rotor is sent to the catalytic reactor, first heated to the reaction temperature of organic matter by the exhaust gas heat exchanger and electric heater, and then under the action of the catalyst, the VOCs molecules are catalytically reacted in the reactor, and the organic matter is converted into carbon dioxide and water.

[0028] Further preferably, the rear end of the catalytic reactor is connected to an exhaust pipe, and the exhaust pipe returns to the front end of the multi-stage filter to form a third heat utilization branch.

[0029] The beneficial effect of adopting the above technical solution is: the exhaust gas containing a certain temperature from the catalytic reactor is returned to the front end of the multi-stage filter, the temperature of the gas rises after mixing, and the relative humidity in the air is reduced by increasing the temperature of the gas, so as to further reduce the moisture content entering the rotor.

[0030] Preferably, the spray tower includes a staggered spray device inside, and further includes a window and a UV lamp; the window is detachably mounted on the spray tower; the UV lamp is fixed outside the spray tower, and the light of the UV lamp is irradiated into the spray tower through the window.

[0031] The beneficial effects of the above technical solution are: the window is detachable, which is convenient for further cleaning of the window. The light of the UV lamp can be irradiated into the tower through the detachable window to accelerate the polymerization and curing of the acrylate.

[0032] Preferably, in order to prevent the glass window from being contaminated by particulate matter in the tower, a compressed air purge device is provided on the inner side of the detachable window tower.

[0033] Preferably, the spray tower further comprises a cyclone device and waterproof adsorbent cotton; the cyclone device is installed at the air inlet of the spray tower; the waterproof adsorbent cotton is installed at the air outlet at the top of the spray tower.

[0034] The beneficial effects of the above technical solution are: the waterproof adsorbent cotton can absorb and retain the solid components of the acrylic acid ester that are polymerized and cured after being irradiated by strong UV light, thereby reducing the UV coating waste gas entering the subsequent processing equipment. At the same time, the adsorbent cotton can play a role in demisting and reduce the humidity of the gas entering the subsequent dry filtration device and zeolite rotor.

[0035] Preferably, several spray towers are used in combination, different spray liquids are prepared according to the composition of the workshop exhaust gas, and a combination of neutralization and oxidation methods is adopted to utilize the principle of acid-base neutralization and peroxide accelerated acrylate polymerization to remove part of the particulate matter and acrylate in the exhaust gas.

[0036] Furthermore, the multi-stage filter is at least a 6-stage filter, and the filter materials of the 6-stage filter are: DPA paint mist filter bag, G4 metal mesh, F5 medium-efficiency chemical fiber bag filter bag, F7 medium-efficiency chemical fiber bag filter bag, activated carbon filter bag, and F9 medium-efficiency glass fiber bag filter bag.

[0037] Preferably, the DPA paint mist filter bag has a removal efficiency of more than 95% for particles ≤10 μm, the filter material is fiber, and the outer frame is aluminum alloy.

[0038] Preferably, the removal efficiency of the G4 metal mesh for particles ≤10 μm can reach over 95%, and the filter material is a metal wire mesh.

[0039] Preferably, the F5 medium-efficiency chemical fiber bag filter is a "V"-shaped filter bag, the effective utilization rate of the filter material reaches 100%, the parts with leakage risk are sealed, and the air outlet surface is ironed to effectively prevent fiber shedding.

[0040] Preferably, the F7 medium-efficiency chemical fiber bag filter bag is a multi-layer composite melt-blown material, the dust-holding melt-blown layer is 40% thicker than ordinary materials, and is partially sealed to prevent leakage risks; an integrated outer frame and ultra-wide inner frame design are adopted to increase the overall structural strength and effectively reduce resistance; the metal edge of the inner frame is rolled inward and flattened to make replacement and maintenance operations safer.

[0041] Preferably, the outer frame of the activated carbon filter bag is made of aluminum alloy, and uses 5mm thick activated carbon fiber cotton filter material; the primary filter is larger than 5μm particles. The activated carbon cotton has high filtering and adsorption strength and low airflow resistance.

[0042] Preferably, the F9 medium-efficiency glass fiber bag filter bag adopts ultra-fine glass fiber, which has stable efficiency and longer service life, and the parts with leakage risk are sealed; the integrated outer frame and ultra-wide inner frame design are adopted to increase the overall structural strength and effectively reduce resistance; the metal edge of the inner frame is rolled inward and flattened to make replacement and maintenance operations safer.

[0043] The technical concept of adopting the above technical scheme is: according to the physical properties of acrylic ester with large molecular weight and high boiling point, activated carbon filter material is used for interception and adsorption in the dry filtration stage, which can give full play to the characteristic that activated carbon is difficult to desorb after adsorbing high-boiling point substances, and adsorb large molecular weight acrylic ester into the pores of activated carbon. The purpose of intercepting and cleaning acrylic ester can be achieved by replacing the filter bag containing activated carbon filter material.

[0044] Since the humidity of the exhaust gas increases after multi-stage spraying, excessive humidity will cause water molecules and VOCs molecules to compete for adsorption inside the zeolite wheel, reducing the wheel purification efficiency; at the same time, since water has a greater specific heat than VOCs molecules, excessive exhaust gas humidity will increase system energy consumption. Therefore, the dry pretreatment unit not only filters particles and VOCs paint mist, but also solves the humidity problem caused by spraying, and can achieve the effect of the zeolite wheel intake humidity below 80%, without affecting the operating efficiency of the back-end equipment.

[0045] Furthermore, in order to achieve the purpose of the invention of this application, the dry pretreatment unit also includes: a humidity probe is added at the tail of the multi-stage filter to monitor the humidity condition entering the subsequent zeolite wheel.

[0046] Preferably, each stage of the filter is equipped with a differential pressure gauge; and each stage of the filter has a transparent door installed at its side entrance and exit.

[0047] Preferably, the wet pretreatment unit uses a combination of several spray towers to prepare alkali solution, peroxide, hydrogen peroxide or water spray liquid, which are used in combination, and a combination of neutralization and oxidation methods is used to utilize the principle of acid-base neutralization and peroxide acceleration of acrylate polymerization to remove part of the particulate matter and acrylate in the exhaust gas.

[0048] Preferably, the catalytic combustion unit includes a plurality of heat exchangers and a multi-stage electric heater, and the rear end of the catalytic reactor is sequentially connected to the desorption heat exchanger and the exhaust gas heat exchanger, and the multi-stage heat exchange fully recycles and utilizes the high-temperature waste heat.

[0049] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the utility model are:

[0050] (1) The technical solution of the utility model is designed based on the factors that trigger the polymerization of methyl acrylate, and these factors are controlled to promote the polymerization of acrylate. Acrylate polymers are collected in the pretreatment stage, so that waste gas containing no acrylate or a small amount of acrylate enters the rear-end "zeolite rotor + catalytic combustion" system, thereby not clogging or damaging the rear-end systems such as the zeolite rotor, pipelines, and heaters, and not affecting the normal use of the waste gas treatment system, thereby ensuring that the waste gas meets the emission standards.

[0051] (2) In the pretreatment stage, a multi-stage spray combination device is used to prepare different spray liquids according to the composition of the waste gas, and the principle of acid-base neutralization and peroxide accelerated acrylate polymerization is used to remove part of the particulate matter and UV paint mist in the waste gas. The swirl spray tower adopts a swirl design, which can use the gas's own kinetic energy to generate a pneumatic swirl, so that the gas and liquid phases are fully in contact.

[0052] (3) The multi-stage filter can effectively intercept 99.99% of paint mist under low wind resistance conditions, and its larger filtration area increases the capacity of paint mist. The multi-stage filter uses chemical fiber bags of different material specifications to filter layer by layer to improve the filtration and interception efficiency. In addition, each level of the filter bag is equipped with a differential pressure gauge to monitor the changes in the filter bag resistance in real time and set the pressure alarm value. Each level of the multi-stage filter uses a transparent door on the side entrance and exit to conduct regular manual monitoring and inspection of the use status of the filter bag. When abnormal conditions are found, timely pressure differential inspection, filter bag damage inspection, filter bag replacement and other measures are carried out to ensure the filtration effect. Monitor the filtration equipment from multiple aspects to ensure the best removal effect of UV paint mist and protect the exhaust gas treatment equipment at the back end.

[0053] (4) The "zeolite rotor + catalytic combustion" system uses multi-stage heat exchange and multi-stage electric heating technology to recycle the heat generated by the decomposition of VOCs into the heating section of the system, forming a heat circulation loop within the system. Through the algorithm analysis of the heat supply, heat loss, and heat emission of the "zeolite rotor + catalytic combustion" system, the entire system can control the energy consumption of the start and stop operation of the electric heater and recycle the heat, thereby reducing the energy consumption of the system operation.

[0054] (5) VOCs molecules are catalytically decomposed into carbon dioxide and water, releasing a large amount of heat energy, and the gas temperature rises to 250-550°C. The catalytic reaction and wheel desorption in the entire system require relatively high temperatures. In order to reduce the energy supply, multiple heat exchangers are connected in series at the rear end of the catalytic reactor that produces high-temperature gas, so that a large amount of heat energy is returned to the heating section of the system for recycling, and a small amount of waste heat is discharged with the purified gas through the exhaust port.

[0055] (6) In order to prevent the exhaust gas from being too humid and affecting the adsorption efficiency of the zeolite wheel, the exhaust gas with a certain temperature from the catalytic reactor is returned to the front end of the multi-stage filter. The heat recovery design within the system solves the problem of high humidity in the gas after passing through the spray tower and reduces energy waste.

[0056] (7) PLC control is adopted to fully automate the on-site equipment through algorithms, thereby further realizing a low-consumption, high-efficiency, and intelligent control mode. Sequential logic control of on-site processes is performed by combining intelligent algorithm logic. Remote monitoring of the operating system can be achieved through mobile phones and computers. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0058] Figure 1 The attached figure is a schematic diagram of the architecture of the VOCs treatment system of the present invention.

[0059] Figure 2 The attached figure is a schematic diagram of heat transfer of the VOCs treatment system of the present invention.

[0060] Figure 3 The accompanying drawing is a schematic diagram of the spray tower of Example 1: 1-air inlet, 2-air outlet, 3-packing layer, 4-demist layer, 5-demist mesh layer, 6-nozzle, 7-UV lamp, 8-detachable window (also inspection port), 9-swirl airflow.

[0061] Figure 4 The accompanying drawing is a schematic diagram of the multi-stage filter of Example 1: 10-inspection door with visual window, 11-air inlet, 12-air outlet, 13-drain outlet, 14-first stage filter, 15-second stage filter, 16-third stage filter, 17-fourth stage filter, 18-fifth stage filter, 19-sixth stage filter.

[0062] Figure 5 The attached figure is a framework diagram of the VOCs treatment system of Example 2.

[0063] Figure 6 The attached figure is a diagram of the VOCs concentration at the inlet and outlet of Example 2. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0065] The current UV paint mist VOCs treatment technology applications all have technical defects to varying degrees, which bring huge safety risks to enterprises, and there is also pressure to stabilize VOCs emissions and meet standards. The reason why the paint mist exhaust gas generated by the use of UV coatings is very sticky is that the acrylic esters in its raw materials are a type of substance that can self-polymerize or copolymerize with other monomers, including methyl acrylate, ethyl acrylate, 2-methyl methacrylate and 2-ethyl methacrylate, etc. Acrylic esters have the physical and chemical properties of easy polymerization and high viscosity at room temperature. They are monomers for manufacturing adhesives, synthetic resins, special rubbers and plastics. However, due to the easy polymerization, the difficulty of treating exhaust gas containing acrylic ester VOCs is increased.

[0066] There are many factors that affect the polymerization of acrylates. Light, heat, peroxides, etc. will accelerate the polymerization reaction. Take methyl acrylate as an example: ① Methyl acrylate will polymerize due to the increase in temperature. The increase in temperature can easily promote the polymerization of low-molecular monomers. As the polymerization proceeds and the heat of polymerization is generated, a large amount of methyl acrylate polymerization will occur, thereby producing a large amount of polymers. ② When there are peroxides that are easy to generate free radicals and other substances with initiating ability, methyl acrylate can easily become an active monomer with free electrons. The active monomer then contacts the methyl acrylate monomer molecule to generate methyl acrylate macromolecules, that is, to initiate the polymerization of methyl acrylate. ③ Under light and radiation conditions, the polymerization of methyl acrylate will also be promoted.

[0067] It can be seen that factors such as light, heat, and peroxide are all positive conditions for causing acrylate polymerization. Once it occurs, it will rapidly increase with the starting polymer as the core, and even at low temperatures, it can form large blocks of polymer, causing pipeline blockage, affecting normal production, causing huge economic losses, and even causing major safety incidents.

[0068] Since acrylates have the physical and chemical properties of being easy to polymerize and having high viscosity at room temperature, when the "zeolite rotor + catalytic combustion" process is used to treat waste gas containing acrylate components, acrylates are easy to polymerize in the pipeline and waste gas treatment equipment, resulting in blockage of the zeolite rotor at the rear end. The zeolite rotor cannot be cleaned after being blocked by the highly viscous acrylate polymer, resulting in the zeolite rotor being unusable, reducing the system treatment efficiency and causing the waste gas to exceed the emission standard.

[0069] In view of this, the utility model provides a VOCs treatment system for UV paint spraying waste gas and a use method thereof.

[0070] Example 1

[0071] This embodiment discloses a VOCs treatment system for UV paint spraying waste gas, including a filtering and concentration system and a heat utilization module connected in sequence.

[0072] The filtration and concentration system comprises a wet pretreatment unit, a dry pretreatment unit and a zeolite rotor adsorption and concentration unit which are connected in sequence.

[0073] Among them, the wet pretreatment unit adopts a combined pretreatment technology of multi-stage staggered spray, that is, a combination of several spray towers in series. The main mechanism of the staggered spray tower is the inertial collision of dust particles and droplets, centrifugal separation and liquid film adhesion. This type of tower plate has a large opening rate and allows high-speed airflow to pass through, so it has a high load, large processing capacity, low pressure drop and greater operational flexibility. The staggered spray tower adopts a swirl design to make the gas rotate and rise. The swirl device is reasonably designed, has a guiding and relay function, and uses the kinetic energy of the gas itself to generate a pneumatic swirl to fully contact the gas and liquid phases.

[0074] To further optimize the above technical solution, see the attached Figure 3 A cyclone device is installed at the air inlet of a single spray tower. The exhaust gas enters the tower from the air inlet 1, and forms a spiral upward airflow 9 under the action of the cyclone device. The tower is provided with three detachable windows 8 and three UV lamps 7. The light of the UV lamp is irradiated into the tower through the detachable windows on the tower. In order to prevent the glass window from being contaminated by particles in the tower, a compressed air purge device is installed on the glass window inside the tower. Adsorption cotton made of waterproof material is installed at the top air outlet 2 of each spray tower.

[0075] To further optimize the above technical solution, see Figure 4 The dry pretreatment unit adopts a 6-stage filter. The filter materials of the 6-stage filter are: DPA paint mist filter bag, G4 metal mesh, F5 medium-efficiency chemical fiber bag filter bag, F7 medium-efficiency chemical fiber bag filter bag, activated carbon filter bag, and F9 medium-efficiency glass fiber bag filter bag.

[0076] Among them, the DPA paint mist filter bag has a removal efficiency of more than 95% for particles ≤10μm. The filter material is fiber and the outer frame is aluminum alloy. The G4 metal mesh can also achieve a removal efficiency of more than 95% for particles ≤10μm. The filter material is metal wire mesh. The F5 medium-efficiency chemical fiber bag filter bag is a "V"-shaped filter bag, and the effective utilization rate of the filter material reaches 100%. The parts with leakage risks are sealed, and the air outlet surface is ironed. The F7 medium-efficiency chemical fiber bag filter bag is a multi-layer composite melt-blown material. The melt-blown layer is 40% thicker than ordinary materials. The parts are sealed to prevent leakage risks; an integrated outer frame and ultra-wide inner frame design are adopted, and the metal edge of the inner frame is rolled inward and flattened. The outer frame of the activated carbon filter bag is made of aluminum alloy and uses 5mm thick activated carbon fiber cotton filter material; the primary filter is larger than 5μm particles. The F9 medium-efficiency glass fiber bag filter bag uses ultra-fine glass fiber, and the parts with leakage risks are sealed; an integrated outer frame and ultra-wide inner frame design are adopted, and the metal edge of the inner frame is rolled inward and flattened.

[0077] In this embodiment, the DPA paint mist filter bag is placed in the first stage to filter UV paint mist and protect the filter bags behind; the pores of the filter bags of F5, F7 and F9 become smaller step by step, among which the F9 filter bag plays a role in ensuring complete exhaust gas filtration in the last stage; the activated carbon filter bag can filter particulate matter and gaseous pollutants at the same time.

[0078] To further optimize the above technical solution, a humidity probe is added to the tail of the multi-stage filter. A differential pressure gauge is installed at each filter stage to monitor the changes in filter bag resistance in real time and set the pressure alarm value. A transparent door is installed at the side entrance and exit of each filter stage to manually monitor the use status of the filter bag at regular intervals. When colored sticky substances appear on the surface of the filter bag or there are many impurities attached to the transparent door, the UV paint mist content in the current filter and the use of the filter bag can be judged, and the pressure difference inspection, filter bag damage inspection, filter bag replacement and other measures can be carried out in time to ensure the filtering effect.

[0079] To further optimize the above technical solution, the zeolite rotor adsorption concentration unit includes a zeolite rotor and an adsorption fan. The zeolite rotor concentrates the exhaust gas by 8 to 20 times, and during operation, it can continue to rotate slowly at a speed of 1 to 8 r / h according to the exhaust gas treatment volume and the concentration multiple requirements.

[0080] The zeolite wheel has three working areas: adsorption area, cooling area and regeneration area. The specific operation process is:

[0081] ① The VOCs molecules contained in the exhaust gas are adsorbed inside the zeolite molecular sieve in the "adsorption zone" of the rotor, and the clean air from which the VOCs molecules are removed meets the standards and is directly discharged into the atmosphere. ② The rotor continues to rotate to adsorb VOCs molecules, gradually tending to adsorption saturation. When the rotor rotates into the "desorption zone", under the purge of hot air, the VOCs molecules adsorbed by the zeolite are sent to the CO system (catalytic combustion unit) through the desorption fan for catalytic combustion reaction. ③ After desorption, the rotor enters the "cooling zone", is purged with cooling air, returns to normal temperature, and rotates again to the "adsorption zone" to restart the next cycle. ④ The clean gas treated in the "adsorption zone" is directly sent to the exhaust pipe through the adsorption fan and discharged into the atmosphere.

[0082] The zeolite rotor concentrates high-volume, low-concentration waste gas into high-concentration, low-volume waste gas, thereby reducing the investment and operating costs of the equipment and improving the treatment efficiency of VOCs waste gas. However, in conventional treatment technologies, the polymerization of acrylates will clog the molecular sieve, making the rotor unusable. The zeolite rotor is a key equipment in the waste gas treatment system. Once the rotor is clogged, it will seriously affect the waste gas treatment efficiency. In addition, the cost of the rotor is high, accounting for about 30% to 50% of the investment in the entire waste gas treatment system. The substandard exhaust gas emissions and economic losses caused by the blockage of the rotor are serious problems, and they cannot be solved in a short period of time, which will further affect the production efficiency of the enterprise.

[0083] This embodiment removes a large amount of UV paint mist through a front-end wet pretreatment unit and a dry pretreatment unit, and adopts a technical solution of a zeolite rotor unit at the back end to overcome the problems in the above-mentioned prior art. The technology of using a zeolite rotor at the back end of this embodiment can be promoted and applied to various industries and various waste gases, with a wide range of applications and high purification efficiency.

[0084] To further optimize the above technical solution, the heat utilization module of this embodiment includes a catalytic combustion unit connected to the rear end of the zeolite rotor, wherein the catalytic combustion unit includes a desorption heat exchanger and a desorption fan.

[0085] In order to further optimize the above technical solution, the rear end of the desorption heat exchanger is connected to the desorption heater and the zeolite rotor in sequence; and the rear end of the zeolite rotor is connected to the front end of the desorption heat exchanger to form a heat utilization branch 1;

[0086] The rear end of the desorption fan is connected to the front end of the exhaust gas heat exchanger; the rear end of the exhaust gas heat exchanger is connected to the electric heater, the catalytic reactor and the desorption heat exchanger in sequence; and the rear end of the desorption heat exchanger is connected to the front end of the exhaust gas heat exchanger, and the front end of the desorption fan is connected to the rear end of the zeolite wheel, forming a second heat utilization branch.

[0087] In order to further optimize the above technical solution, an exhaust pipe is installed at the rear end of the catalytic reactor. The exhaust pipe returns to the front end of the 6-stage filter and mixes with the exhaust gas discharged from the rear end of the multi-stage spray tower. After mixing, the temperature of the gas rises and the relative humidity decreases.

[0088] To further optimize the above technical solution, the method for using the VOCs treatment system of this embodiment includes the following steps:

[0089] (1) The workshop waste gas enters the spray tower, and different spray liquids are prepared according to the composition of the workshop waste gas to polymerize the acrylate. The polymerization and curing of the acrylate are accelerated by UV lamp irradiation. The waste gas passes through the top outlet of the spray tower, and the solid particles and part of the water vapor of the polymerization and curing are intercepted by the waterproof adsorption cotton;

[0090] (2) The workshop exhaust gas from the spray tower enters the multi-stage filter, intercepts and cleans the acrylate through multi-stage filtration, and absorbs the moisture brought by the spray tower to reduce the humidity of the workshop exhaust gas;

[0091] (3) The workshop exhaust gas enters the zeolite wheel adsorption concentration unit. The zeolite wheel continuously rotates to adsorb VOCs molecules. After adsorption saturation, the VOCs exhaust gas is desorbed by the desorption fan and sent to the catalytic combustion unit for catalytic combustion reaction. The zeolite wheel enters the cooling period and enters the next adsorption-desorption-cooling cycle. The clean air from which the VOCs molecules are removed by the zeolite wheel is sent to the exhaust pipe by the adsorption fan and discharged into the atmosphere.

[0092] The zeolite wheel concentrates the workshop exhaust gas by 8 to 20 times and rotates slowly and continuously at a speed of 1 to 8 r / h;

[0093] (4) High-concentration VOCs waste gas enters the catalytic combustion unit, where it is first preheated and heated to the reaction temperature. Then, under the action of the catalyst, the VOCs molecules are converted into carbon dioxide and water through a catalytic reaction, and the treated clean waste gas is discharged through the exhaust pipe.

[0094] Example 2

[0095] This embodiment discloses an application of a VOCs treatment system for UV paint spraying exhaust gas.

[0096] See also Figure 5 The wet pretreatment unit is provided with spray towers 1, 2, and 3, and uses alkaline solution, oxidizing solution, and oxidizing solution as spray liquid respectively. The waste gas treated by the spray tower enters the multi-stage filter 5 under the action of the fan 4, and enters the zeolite rotor 6 after adsorbing acrylate and water. The rear end of the zeolite rotor 6 is respectively connected to the adsorption fan 7, the desorption fan 8, and the fan 13. Under the continuous operation of the zeolite rotor 6, the clean air with VOCs molecules removed enters the exhaust pipe 15 under the action of the adsorption fan 7 and is discharged into the atmosphere; the VOCs gas adsorbed by the zeolite is sent to the catalytic combustion unit by the desorption fan 8 under the hot air purge, and the catalytic combustion reaction is completed in sequence through the exhaust gas heat exchanger 12, the electric heater 9, the catalytic reactor 7, and the desorption heat exchanger 11, and the clean gas is discharged into the atmosphere through the exhaust pipe 15.

[0097] Among them, the rear end of the desorption heat exchanger 11 is connected to the desorption heater 14 and the zeolite rotor 6 in sequence, and the rear end of the zeolite rotor 6 is connected to the front end of the desorption heat exchanger 14 through the fan 13, forming a heat utilization branch one; the rear end of the desorption fan 7 is connected to the front end of the exhaust gas heat exchanger 12; the rear end of the exhaust gas heat exchanger 12 is connected to the electric heater 9, the catalytic reactor 10 and the desorption heat exchanger 11 in sequence, and the rear end of the desorption heat exchanger 11 is connected to the front end of the exhaust gas heat exchanger 12, forming a heat utilization branch two.

[0098] According to “HJ 38-2017 Gas Chromatography for Determination of Total Hydrocarbons, Methane and Non-methane Total Hydrocarbons in Waste Gas from Stationary Pollution Sources”, the VOCs concentrations at the air inlet and outlet were detected, where air inlet point 1 was the exhaust duct of workshop 1#, air inlet point 2 was the exhaust duct of workshop 2#, air inlet point 3 was the exhaust duct of workshop 3#, and the outlet was the discharge port. The specific results are shown in Table 1.

[0099] Table 1

[0100] 1# Inlet point concentration 2# Inlet point concentration 3# Inlet point concentration Outlet concentration 1 321 219 330 0.55 2 108 93 86.4 1.74 3 101 131 98.8 3.21 4 113 128 90.3 3.18 5 108 134 88.4 3.4

[0101] It can be seen that the waste gas treatment system can effectively treat acrylic esters and make the purified gas meet the standards.

[0102] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A VOCs treatment system for UV paint spraying waste gas, characterized in that: It includes a filtering and concentrating system and a heat utilization module connected in sequence; Wherein, the filtration and concentration system comprises a wet pretreatment unit, a dry pretreatment unit and a zeolite rotor adsorption and concentration unit which are connected in sequence; The heat utilization module includes a catalytic combustion unit; The zeolite wheel adsorption concentration unit is connected to the catalytic combustion unit; The zeolite rotor adsorption concentration unit comprises: a zeolite rotor and an adsorption fan; Wherein, the front end of the zeolite rotor is connected to the dry pretreatment unit, and the rear end is connected to the catalytic combustion unit and the adsorption fan respectively; The catalytic combustion unit includes a desorption heat exchanger and a desorption fan; Wherein, the desorption heat exchanger is connected to the desorption heater and the zeolite rotor in sequence, and the rear end of the zeolite rotor is connected to the front end of the desorption heat exchanger to form a heat utilization branch 1; The rear end of the desorption fan is connected to the front end of the exhaust gas heat exchanger, the exhaust gas heat exchanger is connected to the electric heater, the catalytic reactor and the desorption heat exchanger in sequence, and the rear end of the desorption heat exchanger is connected to the front end of the exhaust gas heat exchanger, and the front end of the desorption fan is connected to the zeolite wheel, forming a second heat utilization branch; The rear end of the catalytic reactor is connected to an exhaust pipe, and the exhaust pipe returns to the front end of the dry pretreatment unit to form a third heat utilization branch.

2. A VOCs treatment system for UV paint spraying exhaust gas according to claim 1, characterized in that: Also includes: Exhaust pipe, The tail end of the adsorption fan is connected to the exhaust pipe.

3. A VOCs treatment system for UV paint spraying exhaust gas according to claim 1, characterized in that: The wet pretreatment unit comprises: a plurality of spray towers connected in series; The dry pre-treatment unit comprises: a multi-stage filter.

4. A VOCs treatment system for UV paint spraying exhaust gas according to claim 3, characterized in that: The interior of the spray tower includes a staggered spray device; Also includes, windows and UV lamps; The viewing window is detachably mounted on the spray tower; The UV lamp is fixed outside the spray tower, and the light of the UV lamp is irradiated into the spray tower through the window.

5. A VOCs treatment system for UV paint spraying exhaust gas according to claim 4, characterized in that: A compressed air blowing device is arranged inside the viewing window.

6. A VOCs treatment system for UV paint spraying waste gas according to claim 4, characterized in that: The spray tower also includes a cyclone device and waterproof adsorption cotton; the cyclone device is installed at the air inlet of the spray tower, and the waterproof adsorption cotton is installed at the air outlet at the top of the spray tower.

7. The VOCs treatment system for UV paint spraying exhaust gas according to claim 3 is characterized in that: The multi-stage filter is at least a 6-stage filter, The filter materials of the 6-stage filter are: DPA paint mist filter bag, G4 metal mesh, F5 medium-efficiency chemical fiber bag filter bag, F7 medium-efficiency chemical fiber bag filter bag, activated carbon filter bag, and F9 medium-efficiency glass fiber bag filter bag.

8. A VOCs treatment system for UV paint spraying waste gas according to claim 7, characterized in that: A humidity probe is added to the tail of the 6-stage filter; Each level of the filter is equipped with a differential pressure gauge; and each level of the filter has a transparent door installed at its side entrance and exit.

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